`protected` is an access specifier in object-oriented languages. When the members of a class are `protected`, there is restricted access to these members for other classes.
The protected keyword specifies access to class members in the member-list up to the next access specifier (public or private) or the end of the class definition. Class members declared as protected can be used only by the following:
- Member functions of the class that originally declared these members.
- Friends of the class that originally declared these members.
- Classes derived with public or protected access from the class that originally declared these members.
- Direct privately derived classes that also have private access to protected members.
- In the Java language, classes in the same package as the class that originally declared these members.
